The present invention concerns the electrical connection of the lead wires of a read/write transducer to a preamplifier circuit formed on a substrate and, more particularly, the maximization of the number of electrical connections that can be made on the substrate.
Typically in magnetic disc drives, signals from a read/write transducer are sent to a preamplifier circuit. The preamplifier circuit is generally formed on an electrically insulating substrate, and the resulting assembly is placed as close to the read/write transducer as possible. In many disc drives, it is desired to have the preamplifier assembly located on a rotary arm used to selectively position the transducer over the desired information storage track on the magnetic media on the disc. Such an arm must be capable of responding to positional change commands quickly, and so its inertia is minimized by keeping its mass, and therefore size, as small as possible. Thus, the preamplifier assembly will take up a large amount of the available space on the arm, creating a desire to minimize the size of the substrate.
The electrical connections between the read/write transducer lead wires and the preamplifier circuit are generally made by attaching the lead wires to spaced apart interconnection points on the substrate, with the result that the connections are horizontally spaced in a single plane. In so attaching the lead wires, a minimum distance must be maintained between the positions of adjacent interconnection points to prevent shorting.
A problem that has consequently arisen is that the area remaining available on the substrate for making the interconnection points for electrically connecting the transducer lead wires beyond that needed for the preamplifier circuit is continually decreasing. This is due in part to the use of smaller disc drives with correspondingly smaller rotary arms which have less room for the substrate thereon. Further, the use of increasing numbers of magnetic storage discs in a single disc drive requires a greater number of transducers to be used and therefore increases the number of electrical connections that must be made on the substrate.
In addition to the above pressures, the increasing use of magneto resistive (MR) transducers, many of which use twice the number of lead wires as conventional magnetic transducers, requires that still further electrical connections be made on the substrate.